<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>样式演示</title>
    <style>
        div{
            /*显示边框*/
            border: 1px solid red;
            /*宽度控制*/
            width: 60%;
            /*高度控制*/
            height: 500px;
           /*边框外边距*/
            margin:auto ;
        }

    </style>
</head>
<body>

</body>
</html>